Electric furnace



June 10, 1930. H W STRONG 1,762,201

ELECTRIC FURNACE Patented June 10, 1930 UNITED STATES PATENT OFFICE HERBERT W. STRONG, OF CLEVELAND HEIGHTS, OHIO, ASSIGNOR TO THE STRONG, CARLISLE AND HAMMOND COMPANY, OF CLEVELAND, OHIO, A CORPORATION OF OHIO v ELECTRIC FRNACE Application'ledApril 6, 1928. Serial No. 268,046.

This invention relates to so-called electric furnaces of the type having a walled chamber with refractory wall linings, and heating elements arranged in spaced relation about the walls for heating the same so that the chamber contents may be heated by refiection therefrom.

In such a furnace, for maximum heat capacity relative to the size of the chamber it is desirable to space the globars which are commonly employed as heating elements, as closely together as possible, and to rovide depressions in the wall linings, one or each globar whereby all portions of the inner face of the lining are approximately equidistant from the nearest globar.

An object of my invention is to provide in such and arrangement means whereby the lining may be brought much more quickly to incandescence than would otherwise be possible, and will thereafter function with higher efliciency.

Thismeans comprises, briefiy, forming in the lining a number of relatively small or minor depressions following or making up the general contour of the major depressions; the side portions of these minor depressions meeting to form pointed projections or pro-v jecting ridges of generally triangular shape 80 in cross dimension. The' result is that the pointed or shar extremities of these projections are broug t much more quickly to incandescence than would the corresponding wall portions were they of uninterrupted conformation, and in subsequent operation the extremities Lof these projections are maintained at awhiter heat than would otherwise be the case. v I l The exact nature of my invention-,together with the further objects and advantages thereof, will be apparent from the following description taken in connection with the accompanying drawings in which Fig. 1 is a horizontal section through a typical electric furnaceV in which an 'embodiment of my invention has been incorporated; Fig. 2 is a detail thereof similarly in section; and Figs. 3 and 4 are views corresponding with Figs. 1 and 2 but showing an alternate embodi- 60 ment of my invent-ion.

With reference now to the drawings the furnace is generally of the usualand wellknown construction comprising a heating chamber l immediately bounded by walls 2 of high grade refractory material. The walls may be backed by a layer 3 of fire-brick insulated by a layer 4-of asbestos from a thick covering 5 of heat insulating material all contained within a metallic outer casing 6, access to the chamber l being had through a forward opening 7 lined with fire-brick 8.

Spaced as indicated in the drawings along the side and rear walls of the furnace are a number of vertically extending heating elements or globars 9, commonly of circular section, each positioned by the suitable contactors not shown by which an electric current may be directed through the several globars to bring the same into incandescence when'desired, all as will be well understood by one familiar with the art.

When the globars are thus in incandescent i state it is evident that articles within the chamber 1 will be heated first, bydirect radiatlon from the globars themselves and second, largely by the wall linings which in.

turn receive their heat from the globars. In order that the linings may function to greater advantage it is customary to provide therein parallel depressions 10 whiclrmay be of generally curved section, as arcuate, and concentric with the globars as indicated, whereby-generally the depression surfaces gre equidistant from the corresponding gloars. According to the form of my invention illustrated in Figs. l and 2, I provide the faces of these depressions 10, hereinafter referred to as major depressions, with rela-v tively small minor depressions l1 extending preferably parallel therewith so that in sec.

tion the major depressions have a serrated appearance, the side portions of the minor` depressions meeting angularly to form projecting ridges of generally triangular shape in the cross dimension and havingtheir sharp extremities p12 generally corresponding. in location with the curved contours of the major depressions.

In the form illustrated in Figs. 3 and 4,

the projections between the minor depressions 11 have their sides set at 90, so that said sides are alternately parallel to and normal to the general plane of the lining. As indicated, the sharp extremities l2 of these projections generally correspond in location with the curved contours of the major depressions, as in the case of the form shown in Figs. l and 2.

In either event, it will be apparent that upon functioning of the globars, the projections between minor depressions and particularly 'the sharpened extremities 12, 12 of said projections will be much more quickly brought to incandescence and to a much higher state of incandescence than would the major depression walls were they uninterrupted; the result being that, generally speaking, the major depression walls will be more quickly brought to a higher-.state of incandescence than they would otherwise attain. v

As to the two forms chosen for illustration, that of Figs. 1 and 2 has an advantage in that the projections and consequently the general surfaces of the major depressions are uniformly heated; whereas in the form of Figs. 3 and 4 an advantage is had in that the refractory linings when molded may be withdrawn from the mold by movement in a.

direction normal to the general plane of the lining sections.

While specific illustration and description has been made of minor depressions running parallel with the globars and thus forming projections running in the same direction, my invention also embraces forming the minor depressions in planes transverse to the globars, wherein the projections would extend arcuately about their globars; and likewise the invention embraces running the minor depressions in fboth directions, thus forming projections which instead of being of elongated form would be in the form of individual points or nibs.

lVhat I claim is 1 In an electric furnace, a refractory lining for a wall thereof having a plurality of major depressions, a heating element arranged before each major' depression, each of said major depressions having a curved contour made up of a plurality of minor depressions separated by projections having sharp extremities generally corresponding in loca.- tion with the curved contour of said major depression.

In testimony whereof I hereby ailix my signature.

HERBERT W. STRONG. 

